Metallic beverage can ends are designed to have a stiffening bead extending around each can end adjacent the circumference or periphery of the can end. This bead typically includes generally vertically extending walls interconnected to one another by a bottom wall to form a channel. The bottom wall can be generally rounded or formed into other geometric profiles.
Beverage can bodies and can ends must be sufficiently strong to withstand high internal pressures and also external forces resulting from shipment and handling. Additionally, they must be manufactured from extremely thin and durable materials such as aluminum and aluminum alloys to reduce costs of manufacturing and weight of the finished products. These seemingly incompatible requirements of high strength and light weight can be accomplished by aggressively working the thin materials using interacting male and female tool combinations. Unfortunately, aggressive material working can lead to inconsistencies within a given contour or geometry of can ends due to excessive stretching or thinning of material from which the can ends are made. Such inconsistencies resulting during formation may diminish strength and alter other characteristics of the can ends.
In the present application, techniques for controlling thinning in formed portions of can ends are illustrated in methods and apparatus for forming can ends from thin stock that exhibit required strength and possess improved consistency.